Deconstructing Dyslexia: Blame It On The Written Word

English is notoriously illogical. For example, if "tongue" is pronounced tung, why isn't "argue" pronounced arg? And if "enough" is enuff, why isn't "bough" pronounced buff? The arbitrary rules that govern English bedevil nonnative students of the language as much as they torment would-be spelling-bee champs. But such frustrations pale before those endured by dyslexics, who live with a learning disability that can make reading and writing all but impossible.

In the past couple of decades, scientists have learned a great deal about the neurological causes of dyslexia. But what they hadn't yet explained is why its incidence varies so from...